Masking is a well known technique in Photography and Cinamatography wherein a light transmitting image is made and used in conjunction with another image in order to enhance the final result. The following processes can and often utilize image masking in one form or another; contrast enhancement, contrast reduction, background dubbing, foreground addition, photo version of "chroma cueing", many "special effects", image combining, improving fine detail, false color enhancement, color correction for compensating printing ink or dyes, as well as improving the quality of faded images, and so forth. In fact, the very popular dodging of enlargements and contact prints can be considered as a form of masking in which the mask is positioned well out of the focal plane. Many techniques involved in producing "posturized" pictures can also be thought of as utilizing photo masks.
Photographic masks can be sharp of the in-focus type or unsharp of the out-of-focus type. They can be positive or negative, continuous tone or single tone, opaque or semi-opaque, black and white or color and are most often used in register with the image to be enhanced.
Masks are usually made from or in conjunction with the image being enhanced, however, masks can also be made by hand and/or from suitable materials or pigments.
In many cases, these masks are used in printing in a one-step subtractive manner in which the masks selectively remove from the picture being enhanced some of the light normally transmitted while it is being printed. In an additive mode, the mask often removes all of the light from the selected areas of the picture and in a subsequent multiple exposure these areas are exposed in connection with another picture combined with a complimentary opaque mask.
One of the short comings of the above techniques, is that the final enhanced result is often not known until the final image has been recorded and processed. This is particularly true when working from negatives to positives. It is also true when working with a multistep additive process. Another difficulty with masking techniques as utilized today is that often there is very little control over the final result except to remake the mask. Another limitation is that most masking techniques are limited to the use of only one mask at a time. Also, the problem of image registration often presents difficulties.
The following multichannel masking technique and equipment will overcome the above difficulties and provide a tool for producing other special effects more economically than computer operated laser printers and more conveniently than the usual darkroom techniques.
An object of the present invention is to provide an improved image enhancement apparatus for use in producing improved enhanced Photography and Cinamatography.
Another object of the invention is to provide an apparatus for controlling the enhancement of images while one is observing the results of the enhancement before recording the resulting image.
Another object of the invention is to provide a masking system with improved precision image registration.
Still another object of the invention is to provide a multichannel combined imaging and projection system for the production of special photo effects.
Another object of the invention is to provide an improved multi-imaging system in which several images are combined and precisely registered to provide enhanced images and special effects.
A further object of the invention is to provide a film holder which insures precise registration of several images, each with the other when the film is being exposed and after processing for projection of the processed film when it is returned to the identical position for projection back through the same optical system.
Yet another object of the invention is to provide an imaging system with "in situ" processing and means for projecting an image back through the same optical system in order to insure precise image registration for precise masking and special effects.
Other objects and advantages will appear as the following detailed description proceeds.